Week 3 Flashcards
what are the functions of the cardiovascular system?
transports oxygen, hormones, and nutrients to cells
removed CO2 and waste from the body
regulates body temp. (vasodilation/constriction)
name the location and size of the heart
located in the thoracic cavity, under sternum, sits on diaphragm, flanked by lungs
base near the 2nd rib, apex points to left hip at above the 5th rib
size of a clenched fist
name the chambers, veins and arteries branching off the heart (and their functions)
right atrium- receives deoxygenated blood via vena cava
right ventricle- pumps blood to body via aorta
left atrium- receives oxygenated blood from lungs
left ventricle- pumps blood to body through aorta
name the valves within the heart
atrioventricular valves
- allows blood flow from atria to ventricles, prevents back flow
- right valve is tricuspid
- left valve is bicuspid
semilunar valves
- controls flow from ventricles to lungs/body
- pulmonary valve (right, leads to lungs)
- aortic valve (left, leads to body)
name any walls/support structures in the heart
- chordae tendinae attach to papillary muscles to help secure AV valves during contractions
- Heart is enclosed in fluid-filled pericardium sac, outer wall anchors to surroundings, inner wall (2 layers filled with fluid) facilitates frictionless heartbeats
- epicardium (heart outer wall) is also inner layer of pericardial sac
- myocardium (middle) 2/3 of heart’s muscle (pumps blood)
- endocardium (inner) lines chambers, valves (frictionless blood flow)
describe the flow of blood through the cardiopulmonary system
- deoxygenated blood enters from inferior and superior vena cava into the right atrium
- tricuspid valve opens due to pressure, right ventricle fills passively (completed by atrial contraction)
- right ventricle contracts, tricuspid valve closes, pulmonary valve opens
- blood is oxygenated through capillaries in the lungs
- oxygenated blood returns via pulmonary veins
- mitral valve opens from pressure, left ventricle fills passively (completed by atrial contraction)
- left ventricle contracts, mitral valve closes, aortic valve opens
- oxygenated blood is distributed through the body
what is cardiac output and how would you calculate it?
volume of blood pumped per minute (heart rate x stroke volume)
what is diastole and systole?
diastole (relaxation of ventricles)- chambers fill with blood
systole (contraction of ventricles)- chambers pump blood out
when ventricles are contracted, atria are relaxed
how does blood flow from the arteries to the veins?
what is the mechanism of internal control of heart rate?
pacemaker sinoatrial (SA) node
- located in right atrium (near superior vena cava)
- generates electrical impulses that instruct a steady rhythm (60-100 bpm default)
what are the two mechanisms of external control of heart rate?
cardiac centre
- receives input from autonomic nervous system
- adjusts heart rate, contraction strength, stroke volume
- baroreceptors monitor blood pressure (sympathetic nervous system increases heart rate during stress/exercise, parasympathetic nervous system slows heart rate during rest)
endocrine system
- influenced by emotions, physical activity (e.g. fight-or-flight)
- sympathetic NS releases noradrenaline -> increases heart rate
- parasympathetic NS releases acetylcholine -> relaxes heart
what are the three factors that control stroke volume?
preload
- extent to which ventricle muscles are stretched during diastole (filling)
contractility
- ability to contract (influenced by preload)
- higher preload -> stronger contractions -> more stroke volume
afterload
- resistance on ventricles (aortic pressure) against ejecting blood
- higher after load -> reduces stroke volume
explain the conduction system of the heart
nodal tissue and conduction fibres transmits electrical impulses that tell ventricles when to contract (regulates heart rate)
- sinoatrial (SA) node: initiates impulse (sends to left atrium, atrioventricular node)
- AV node delays impulse (0.1 sec)
- bundle of His (in ventricular septum) divides signal into left/right bundle branches to reach millions of purkinjie fibres in ventricles (triggers them to contract)
what is the electrocardiogram (ECG) and its three waves?
graphical representation of the heart’s electrical activity
P wave- indicates activation of sinoatrial node and contraction of atria
QRS wave- indicates impulse reaching purkinjie fibres leading to ventricular contraction
T wave- indicates ventricular relaxation and chamber filling
what are the three layers in blood vessel walls?
tunica intima
- smooth frictionless surface
- squamous epithelial cells
tunica media
- smooth muscle, controls vasodilation/constriction
- elastic fibres/collagen
- influences blood pressure
tunica externa
- fibrous tissue, adds support
what are the different types of blood vessels and the differences between them?
arteries (arterioles), veins (venules), capillaries
- arteries have thick, strong walls to carry blood away from the heart (high pressure)
- veins have more elastic walls to carry blood toward the heart
- one-way valves in veins assist return, as well as skeletal muscles and respiratory system
- capillaries are the body’s smallest vessels and bridge arterioles and venules (forms capillary beds)
- capillaries are a site for O2/CO2 exchange, red blood cells pass in single file
- capillaries do not have 3 layers in their walls but sometimes possess pores for passage of hormones and white blood cells (for immune responses)
how does the heart receive its oxygen (cardiac circulation)?
left/right coronary arteries on its surface
- starts at base of aorta, fills when ventricles are relaxed, closes during contraction (high pressure)
- blood is directed into cardiac veins -> coronary sinus on posterior wall of right atrium
